Photoshop Eraser and brush tools not working

I used Photoshop yesterday and it worked fine, but today I tried to use both the brush and eraser tools and they just aren't doing their jobs, both and 100% opacity, both used on multiple sizes and modes.
I tried resetting the tools but they still aren't working. I need to edit my images for my university course as they're due in very soon.

Hi! Did you get an answer? I'm not a tech, I'm a user and tried to duplicate your issue. I've noticed on several of the PS tools that some of the 'options' like 'smoothing' or 'flow' change and I didn't do it. Sometime the 'Mode' changes too. Try the tools on a brand new file and just pick a brush and paint and then try erase. Maybe an area has been accidently selected. I'll keep looking. Good Luck!

So far it's fixed itself when ever I close down my ps and reopen everything, but after maybe half an hour or so it does the exact same thing. I can deal with the issue because it does occasionally work and I don't need to be on it full time, but if anyone can help that would be great